A) Field of the Invention
The present invention relates to a dry multi-disk clutch assembly for use in a motorized vehicle. More particularly, the present invention relates to a multi-disk clutch having a plurality of clutch disk elements disposed within a cylindric drum shaped member and having limited axial movement relative thereto. The cylindric drum shaped member and other clutch elements are formed with air holes to prevent excessive heating and diaphragm spring engaging portions to reduce wear.
B) Description of the Related Art
Clutch mechanisms having multiple clutch disks are well known. Clutch mechanisms typically include a clutch cover assembly whose outer periphery portion is fixed to a flywheel, an annular pressure plate provided inside the clutch cover, a diaphragm spring which, by its resilient force, urges the pressure plate towards multiple clutch friction disks sandwiched therebetween, and a support structure within the clutch cover to support the diaphragm spring.
Generally, dry multi-disk clutch assemblies are often used for automotive racing applications. As such, a hub flange is disposed between the flywheel and the pressure plate, the hub flange having a hub connected to a transmission shaft, a flange that extends from the hub to the outer periphery, and a drum-shaped element that is provided on the outer periphery of the flange and projects to opposite sides of the flange, the clutch friction disks being located in the space between this drum-shaped element and an outer flywheel ring which encircles and encloses the multiple clutch disks. One end of the space in which the friction disks are installed faces a surface such as that of the flywheel, etc. against which the friction disks are pressed, and the other end faces the pressure plate.
The support structure generally includes a ring element that engage one surface of the diaphragm spring, and bolts which fix the ring element to the clutch cover, thus retaining the diaphragm spring therebetween. The ring element engages an inner surface of the clutch cover. Projections or leg members at plural locations are fixed to the clutch cover by bolts.
The diaphragm spring deforms in response to the clutch engagement action and disengagement action and exerts pressure in various directions on the ring element. In response to this, the ring element tries to move with respect to the clutch cover.
In a conventional structure, the ring element is literally a ring possessing a cross-section with an approximately circular shape, and its area of contact with the clutch cover is small. Consequently the contact pressure between the ring element and the clutch cover is large.
As a result, great wear occurs in the clutch cover portions that contact the ring element. One reason why the clutch cover becomes worn is that the ring element is typically made of steel, whereas the clutch cover, in order to reduce weight, is typically made of metal consisting mainly of aluminum.
The occurrence of wear in the clutch cover results in slippage of the ring element position, and consequently in distortion of the diaphragm spring's operating characteristics. Also, if its wear progresses to a considerable extent, the clutch cover has to be replaced.
With the above structure, the inner periphery and outer periphery of the friction disk installation space are enclosed by the drum-shaped element at the hub flange's outer periphery and the flywheel ring, and at opposite axial ends are enclosed by the flywheel and by the pressure plate and the clutch cover. With this structure, there is only limited air flow. Air may only flow from outside into the area of the clutch disks through a narrow gap that is between the pressure plate and a hub flange outer periphery end portion and go as far as the surfaces of the friction disks that are near this gap. It is therefore not possible to cool the friction disks effectively, and, in particular, the cooling effects for friction disks that are not adjacent to the pressure plate are extremely poor. As a result, the friction disks become overheated. Overheating of friction disks can cause serious problems relating to their operating characteristics and durability.
The multiple clutch disks usually include alternating driven and drive plates, the drive plates engaging the flywheel ring (which rotates with the flywheel) and the driven plates which rotate with the transmission shaft. The range of axial displacement of the drive plates and driven plates is restricted by the flywheel and the pressure plate. The axial position of the hub flange is kept within a set range by a protrusion or pin that may disposed in the hub flange, the pin or protrusion being attached to an outer radial surface of the hub flange and extending radially between two adjacent the drive plates.
There are two possible problems associated with the positioning pin. First, the pin may effect the moment of inertia of the overall flywheel mechanism and of the hub. Second, if the pin is disposed in a hole formed in the flange hub, there is a possibility of the pin coming out of the hole of the due to heat or vibration produced at the time of clutch coupling.